I played this game for quite a while, and if I hadn't forced myself to stop, I would have spent hours playing it. Your game has a very original concept, wonderful fluid gameplay, and a skill tree that, just by appearing on the screen, makes me excited to see what I can and can't buy. I admit that playing with the keyboard isn't as satisfying as playing with the mouse, but it's still fun and doesn't spoil the experience at all.
I really want to see this game with more upgrades, more skills, and different combos, as the guy in the comment below mentioned.
~ Congrats on creating this jewel!